burning blue smoke and very dirty (new) spark plugs

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CrookedRows
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Zip Code: 01742
Tractors Owned: 1947 Farmall Cub
Location: Concord, MA

burning blue smoke and very dirty (new) spark plugs

Postby CrookedRows » Thu Sep 03, 2015 8:18 pm

Hi Folks,
This past winter my partner and I purchased our first tractor, a 1947 Cub, to help out around our little farm. When we bought her, a bit of work was needed to get her up and running (which the mechanic did). Since she's come to our little farm, she has become quite essential to our little operation. So much, that when the tractor started not working, we've been struggling to return to the laborious ways of farming by hand.
She always smoked a little bit after starting up, but would stop after a few minutes of running. The engine sounds great. But as the season progressed, she smoked more and more and would continue smoking during operation. Eventually she would loose power and the engine would struggle and finally it got bad enough that I started to try and figure out what the issue was. I ended up replacing the distributor cap as the contacts were quite corroded, new dust cover and cleaned off the pinion gap (i might need to be corrected on what I'm talking about here). It should be noted that I had noticed some moisture build up in the distributor cap, not a lot, but enough to make me notice. While I was at it, I also replaced all four very dirty spark plugs. Finally, I also replaced the gas filters as they had accumulated quite a bit of rust (from the gas tank) in the filters which were inhibiting the flow of gas. She then ran like new again for a couple weeks before the troubles really started.
She still is belching blue smoke and after a few minutes of running, the engine really struggles to keep power and just tries to keep chugging, but sounds like a dying, belching, cow. After limping back to barm, I looked it over again and noticed that the first (in the firing order) spark plug had some moisture build up on the spark plug (this is seen on the exposed plug and again more moisture when removed). I have a suspicion this is oil. The other spark plugs, after being removed, are also incredibly gunked up. I don't have a lot of experience with this stuff, but it looks like a lot of carbon build up. Remember, these plugs are only a few weeks old and they look like they've been in use for years. Cleaning the plugs didn't seem to help much, though I didn't have the time to do a decent job with them either.
So, that's as much information as I have. Poking around the internet, my suspicions to the causes of all this are:
- bad seals/gaskets somewhere leaking oil into the engine
- carb burning too rich?
- bad batch of spark plugs (unlikely, but you never know)

Any help on what to do next would be much appreciated. I don't have a great deal of mechanical experience, but I have a full set of manuals that I bought for the cub and I'm willing to do as much as I feel comfortable doing on my own.

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Re: burning blue smoke and very dirty (new) spark plugs

Postby staninlowerAL » Fri Sep 04, 2015 5:52 am

Your oil fouled spark plugs and burning blue smoke problem sound typical of worn piston rings. Moisture on the plug might be condensate or worse, a leaking head gasket. A weak running engine might be symptomatic of a need of valve lash adjustment and a complete tune up. It will be helpful to know the compression test results of each cylinder both wet and dry as well as the oil pressure on startup as well as after the engine is warmed up to help diagnose the condition of your engine. Any past history of engine repair/overhall? Sounds like a tired, 1947 Cub in need of a engine rebuild. Hope this is helpful. Stan

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bob in CT
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Re: burning blue smoke and very dirty (new) spark plugs

Postby bob in CT » Fri Sep 04, 2015 7:26 am

I agree with Stan, that you probably have worn rings, but the chugging also sounds like you still have a fuel delivery problem.

There is a screen at the fuel inlet that is worth checking. Loosen the fuel line and then you may want to loosen the carb at the manifold to get the line out for inspection. I recommend threading the line back in after inspection with the carb loose, so you make sure not to cross the threads in the pot metal casting when you are starting it. If the fuel line is not perfectly bent, it is easy to create a problem.

You can see the screen here:

Image

The most likely culprit is a gunked up jet and that is easy. Remove the brass nut shown below and clean it with some compressed air or some soft copper wire strands.


Image

You can download a service manual that will take you through the valve lash adjustment as well as all the major tasks in servicing your tractor.

http://www.farmallcub.com/[ Sorry, direct links to manual section is not allowed. ]/download.php?fname=./files/Service%20Manuals/Blue%20Ribbon%20Service%20Manuals/GSS-1411%20W-Rev%201%20Cub%20and%20Lo-Boy%202-76%20OCR.pdf

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Stanton
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Re: burning blue smoke and very dirty (new) spark plugs

Postby Stanton » Fri Sep 04, 2015 10:13 am

Welcome to the forum!

Good advice from Stan and Bob above. I'd steer clear of using Champion plugs; too many have had trouble with them. I'd suggest Autolite 386's.

If you haven't already, check out the wealth of information using the above links across the top of the screen to access Manuals. Also might read the Welcome Wagon (http://www.farmallcub.com/phpBB2/viewtopic.php?f=20&t=88707) and the How To Forum.
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Re: burning blue smoke and very dirty (new) spark plugs

Postby Papa's Cub » Fri Sep 04, 2015 11:05 am

Well, you stated it smoked blue for a few minutes when first started, but, didn't follow up with how much oil it consumed per hour, half day, etc.. I had a cub like this a few years back and installed 4 fowlers on the plugs. It continued to use oil and smoke like a freight train, but, ran as slick as Mama's old sewing machine. I suspect you also have a fuel restriction and probably need to re-adjust the valves. In other words, give her a complete tune-up. Oh, might try adding some fuel additive to the gas tank too. Just a thought, good luck, Tom.
If you always do what you've always done -- you'll always get what you've always got!

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indy61
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Re: burning blue smoke and very dirty (new) spark plugs

Postby indy61 » Fri Sep 04, 2015 11:16 am

If you have a magneto I would use Autolite 3116 non-resistor plugs. Points gap: .013”

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CrookedRows
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Tractors Owned: 1947 Farmall Cub
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Re: burning blue smoke and very dirty (new) spark plugs

Postby CrookedRows » Fri Sep 04, 2015 1:37 pm

wow, you folks are amazing!
There's a ton of information for me to wade through here and I'll try to keep everyone up to date as I progress with my troubled cub.
to answer a few questions:
@Stanton and @Indy61 - the replaced spark plugs are indeed Autolite 386's . I'll check out the 3116 next time i'm in a shop. Also, thanks for the tip on the Welcome Wagon. Looks like some great info in there! I can't wait to get into it.
Papa's Cub wrote:Well, you stated it smoked blue for a few minutes when first started, but, didn't follow up with how much oil it consumed per hour, half day, etc.. I had a cub like this a few years back and installed 4 fowlers on the plugs. It continued to use oil and smoke like a freight train, but, ran as slick as Mama's old sewing machine. I suspect you also have a fuel restriction and probably need to re-adjust the valves. In other words, give her a complete tune-up. Oh, might try adding some fuel additive to the gas tank too. Just a thought, good luck, Tom.

Ah good point, I haven't been keeping an eye on the oil levels and probably should.

bob in CT wrote:I agree with Stan, that you probably have worn rings, but the chugging also sounds like you still have a fuel delivery problem.

There is a screen at the fuel inlet that is worth checking. Loosen the fuel line and then you may want to loosen the carb at the manifold to get the line out for inspection. I recommend threading the line back in after inspection with the carb loose, so you make sure not to cross the threads in the pot metal casting when you are starting it. If the fuel line is not perfectly bent, it is easy to create a problem.

The most likely culprit is a gunked up jet and that is easy. Remove the brass nut shown below and clean it with some compressed air or some soft copper wire strands.

You can download a service manual that will take you through the valve lash adjustment as well as all the major tasks in servicing your tractor.

http://www.farmallcub.com/[ Sorry, direct links to manual section is not allowed. ]/download.php?fname=./files/Service%20Manuals/Blue%20Ribbon%20Service%20Manuals/GSS-1411%20W-Rev%201%20Cub%20and%20Lo-Boy%202-76%20OCR.pdf

Ah! I forgot about the screen on the carb. The carb looks fairly old and so I can only imagine when the screen was last cleaned out. That should at least help a bit.

I'll keep posting as I go along.

Clip
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Re: burning blue smoke and very dirty (new) spark plugs

Postby Clip » Sat Sep 05, 2015 6:21 am

Losing power and blue smoke sounds like worn rings. Have you done a compression test?

DDean
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Tractors Owned: 1949 Farmall Cub
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Re: burning blue smoke and very dirty (new) spark plugs

Postby DDean » Sat Sep 05, 2015 7:43 am

Seafoam straight - down the spark plug holes and let sit for a couple days, about a tablespoon or so in each plug hole. If you have stuck rings, this can release them, it removes the carbon that is causing the rings to stick in the piston grooves. If this helps, then you could move on to replacing the head gasket and cleaning valves and seats for adjustments, which if it was burning oil, then you will probably have carbon build up on valves and seats which needs to be cleaned before adjusting them. You can also look at cylinder walls, valves and seats and water jackets while your replacing the head gasket for damage, carbon build up or excessive wear and plugging up of water jackets.


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